In a gas turbine, there is a gap between the picture frames in the combustor outlet and the first vane of the turbine. Movement of the two parts relative to one another can be considerable, and a gap must be left between the parts to avoid contact. The gap is generally purged with cooling air. It has been appreciated that it would be advantageous to improve the design around this gap to, for example, reduce the cooling air requirements.
Annular hula seals are known from, for example, US 2012/0304657 and US 2010/0300116.